Circuit breaker



June 20, 1961 E. M. WEGH 2,989,604

CIRCUIT BREAKER Filed April 4. 1957 5 Sheets-Sheet 1 INVENTOR. 13m-lEMERY M. WEGH ATTORNEY June 20, 1961 E. M. wEGH 2,989,604

CIRCUIT BREAKER Filed April 4, 1957 5 Sheets-Sheet 2 '2.7 INVENTOR.

EMERY M. WEGH NM2? CM ATToR/vey June 20, 1961 E. M. wEGH 2,989,604

CIRCUIT BREAKER Filed April 4, 1957 5 sheets-sheet s INSULATION IN VENTOR.

ENERY M. wie" ATTORNEY vJune 20, 1961 E. M. wr-:GH 2,989,604

CIRCUIT BREAKER Filed April 4, 1957 5 Sheets-SheetA INSULATION NSULATIONINSULATION INVENTOR. E MERY M. Ween BY but? Ano/miv June 20, 1961 E. M.wEGl-l 2,989,604

CIRCUIT BREAKER Filed April 4, 1957 5 sheets-sheet s if l W l willi iil* I g Y' I4 INVENTOR.

EMERY M. WEGH United States Patent O n 2,989,604 l i CIRCUIT BREAKEREmery M. Wegh, Terryville, Conn., amignor to General Electric Company, acorporation of New York Filed Apr. 4, 1957, Ser. No. 650,600" 9 Claims.(Cl. 200-88) My invention relates to electric circuit breakers andparticularly to multipole electric circuit breakers of the typeincluding a molded insulating casing and adapted for use, either ysinglyor in panelboards, for the control of electric light and power circuitsin residential, commercial, and industrial buildings.

In recent years, relatively small, compact, plug-in type single-polecircuit breakers have become popular for use in residential, commercial,and industrial buildings. A circuit breaker of the type referred to isshown, for instance, in Patent No. 2,627,563, issued February 3, 1953,to W. A. Thomas and assigned to the same assignee as the presentinvention. Panelboards of the type containing contacts adapted toreceive such plug-in circuit breakers, also in wide use, are shown inPatents Nos. 2,738,445,

2,989,604 Patented June 20, 1961 above-mentioned Getchell patent, whichwould be completely impracticalin the present instance.

In addition, thesize of the compact plug-in type circuit breakersinvolved herein is such that more than one-half the interior space istaken up by the necessary arc extinguishing chambers and currentresponsive trip devices. These two components, which are normallypositioned at opposite ends of a circuit breaker, with the mechanismtherebetween (see Getchell patent) are, ink compact breakers of the typeof the Thomas patent, virtually brought adjacent each other, leaving noroom to mount a mechanimi-therebetween and making it necessary toutilize the upper portion of the housing for the mechanism.

It is therefore an object of my invention to provide a circuit breakermechanism which is extremely compact yet capable of providing relativelyhigh contact pressures.

It is a further object of my invention to provide a high contactpressure 'type of circuit breaker mecranism which and 2,738,446,1SsuedMarch 13, 1956, to H. J. Hammerly et al. and to W. I. Fleming,respectively, and also assigned to the same lassignee as the presentinvention.

Such compact plug-in circuit breakers have heretofore been availableonly in single-pole and two pole forms,

rated 10 to 50 amperes `at 125 volts. There has for some time been aneed, however, for three-pole circuit breakers of this t'ype and size,which can also be plug-in mounted in such panelboards. Such three-polecircuit breakers have heretofore not been available because of theditlculty of providing one which will meet the electrical requirementsin the small space available. Such a breaker must, for instance, berated at subsequently ydouble the voltage of the single land ytwo-poledevices, i.e., 240 volts, and at currents of the same or greater value,i.e., 10-70 amperes, while occupying substantially thersame space perpole as the single-pole version.

The-problem is further illustrated by comparing the size of the requiredthree-pole plug-in breaker with that of a three-pole breaker ofrsimilarrating in general use .f

breaker is approximately three tirnes` the Size of the breaker of thepresent invention.

It is, therefore, a general object of my invention to provide anextremely compact and ecient multipole circuit breaker and especially acompact and ecient plug-in type multipole circuit breaker, suitable foruse in existing plug-in type panelboards.

In providing such a compact multipole circuit breaker of increasedrating, it is necessary to provide a high amount of contact pressure ina relatively small space. In circuit breakers of the type shown in' theabove mentioned Thomas patent, the contact pressure normally provided isin the neighborhood of 14 to 17 ounc between the contacts in the closedcircuit position. In applicants subject invention, however, the contactpressure for each is able to be contained in the top portion of acircuit breaker housing and adapted to operate a movable contact movingwithin the bottom portion of such circuit breaker housing.

Another object of my invention is the provision of an electric circuitbreaker operating mechanism including operating spring means which isremoved from the portion of the circuit breaker casing where arcinterruption takes place, to minimize the possibility of damage to suchspring means by are gases.

It is` a further object of my invention to provide such an electriccircuit breaker mechanism which provides a quick make `and quick breakor snap action, which cannot be retained during tripping in the onfposition by manual force, which indicates by a unique position of itsoperating handle that an automatic opening operation has occurred, andwhich is capable of controlling contacts for two or three circuitssimultaneously.

In accordance with my invention, I provide a circuit breaker mechanismincluding a movable switch member pivotally supported on a `fixedpivotal axis, a manually operable handle member pivotally supported onanother fixed pivotal axis, a releasable trip member pivotally supportedon a third xed pivotal axis and retained in a normal latched position bya current responsive latch member, and means interconnecting the handleand the switch member including a pair of toggle links and an operatingspring, all of the aforesaid fixed pivotal axes being arranged in anovel compact arrangement, whereby the length of travel of the movablecontact and the amount of contact pressure are-both maintainedrelatively high while the over-all size of the mechanism is drasticallyreduced. I further provide a circuit'breaker mechanism of the typedescribed above in which the pivotal axis of the releasable trip memberand the pivotal axis of the movable switch member are both on the sameside of the line formed by the toggle links in their set `condition, andrelatively close together resulting in a mechanism which is very compactand which also can be of three sets of contacts is in the neighborhoodof 28 to 'l i mounted in the upper part of a circuit breaker housingwhile` operating a movable contact in the lower part of the housing.

In accordance with another aspect of my invention, I provide a circuitbreaker including a generally rectangular casing with a handle at thetop and relatively stationary contacts adjacent the bottom, the housingis split into substantially equal top and bottom portions with theaforesaid pivotal axes all being contained in the top portion.

iIn accordance with a still further aspect of my invention, theoperating mechanism is preassembled in its own supporting frame and ismerely inserted into the corresponding recess in the top. `It isaccurately positioned by projections carried by the outer sides of theframe .5 and received in tapering grooves in the casing walls. The

assembled mechanism is retained in the recess, when the top and bottomare assembled, by retaining means carried by the bottom part acting oncompressible portlons of the side frames.

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter which I regard as myinvention, it is believed the invention will be better understood fromthe following detailed description taken in connection with theaccompanying drawings in which:

FIGURE 1 is a side elevation View of la three-pole circuit breakerconstructed in accordance with my invention, the side of the enclosinghousing being removedto show the parts, and the circuit breaker beingshown in the normal open-circuit condition; 'Y

FIGURE 2 is a side elevation View similar to FIGURE 1 but with thecircuit breaker shown in the closed-circuit `condition;

' FIGURE 3 is a side elevation view similar to FIGURE 1 but with thecircuit Vbreaker shown in the automatically opened or tripped condition;

FIGURE 4 is an exploded view of the insulating housing of the circuitbreaker of FIGURE l, shown as in FIGURES l-3';

FIGURE 5 is a perspective view of the operating mechanism and movablecontact assemblage of thecircuit breaker of FIGURE 1 parts thereof beingbroken awa FiIGURE 6 is an exploded view of the parts of the circuit.breaker of FIGURE 1, including the operating mechanism, movable contactassemblage, and one line terminal, arc chute, trip device and loadterminal;

FIGURE 7 is an end elevation View of the circuit breaker of FIGURE 1 asviewed from the line terminal end;

FIGURE `8 is an end elevation View of the circuit breaker of FIGURE 1 asviewed from the load terminal end, a portion of one of the load terminalclamping members being broken away;

FIGURE 9 is an exploded view of the circuit breaker of FIGURE 1 asviewed from the side thereof;

y FIGURE l0 is a View of the top housing member, taken on the line 10-10of FIGURE 9, the operating mechanism and trip devices being omitted;

FIGURE ll is a View of the bottom housing member taken on the line 11-11of FIGURE 9, one of the arc extinguishing structures being omittedandtwo 'arcextinguishing chamber covers being omitted;

FIGURE l2 is a detail view showing a modified form of common trip barfor use in the circuit breaker of FIGURE l; and FIGURE 13 is a sectionalView of a modified form adapted for two-pole circuits.

Certain aspects of the circuit Vbreaker disclosed herein other than themechanism per se, are disclosed and claimed in an `application filedconcurrently herewith by Emery M. Wegh and George W. Kiesel andassigned'to the same assignee as the present invention.

In the drawings, I have shown my invention as ernbodied in a three-poleelectric circuit breaker having a generally rectangular insulatinghousing comprising a top housing member 10 and a bottom housing member11 adapted to be connected together by suitable means such as by tubularrivets 12, FIGURE 9, passingthrough holes 1'4, FIGURES 10 and 1l, in thetop and bottom housing members respectively. Referring to FIGURES 1,0and 11, the top housing member `10 has three elongated recesses 15, 16and 17 extending substantially from end to end thereof and separated bybarriers 18 and 19integral with the top housing member. The bottomheusing member 11 is also provided with three elongatedgenerallyparallel recesses 20, 21 and i22 thereinfseparated by barriers 23 and`2.4 also integral with the bottom lhous-V ing member. The recesses inthe top and bottom housing members are contiguous when the housingmembers are assembled together and define three side-by-side generallyrectangular pole chambers, there being one such pole chamber for eachpole of the circuit to be controlled.

Each of the recesses 20, 21 and 22 has supported within it at one endVthereof la plugin type line contact socket 25. 1 The socket 25comprises a generally Uf shaped member (see FIGURE 6) having the legsthereof brought closer togetherat their extremities than at the bight ofsaid U,V and a generally U-shaped resilient reinforcing clip member 26embracing the sides of said U- shaped linev contact member adjacenttheirextremities. The bottom housing member 11 is provided -with ,threeL-shaped corner slots 27 providing access ,to said line con` tact socket25 by suitable `means such as by a bladetype Contact (not shown).

The line contact socket 25 further includes a contact supporting portion28 integral therewith and-extending froml the bight of saidv U andhaving a stationary contact 29 fxedly attached thereto by suitablewmeanssuch as by welding.

For the purpose of cooling and extinguishing 'arcs adjacent saidstationary contact 29, I provide arc extinguish# ing means adjacent eachofthe stationary contacts 29 and including ja generally U-shapedinsulating Support 30, V(see particularly VFIGURES 6 and 1l). TheU-shaped insulating member 30 Vis preferably formedof a strongsheetinsulating material such as vulcanized cellulosic fiber, andsupports between the sides thereof a plurality of notched metallic arcextinguishing plates 31. The U-'shaped in sulating piece 30 is supportedyin place by the corresponding outer Walls of the 'bottom insulatinghousing member 11, by portions of the barriers 23 and 24, and `also byshort transversely extending barriers 32 integral lwith the outer wallsandthe barriers of the bottom vhousing member V11. The transverselyextending barriers 32 are cut away or notched to Aprovide an entranceportion 33yto yeach of thearc extinguishing chambers.

The stationary contact supporting portion'of Ythe line contact 25extends over the top edge ofthe bightwall ofthe Ushaped member 30,thereby supporting/'the line contactmember Y25 vin place in the recess20.` The line contacts 25 are further'supported in their respectivechambers by shoulders 34 integral with the bottom insulating housingmember 11 which are adapted to engage cor- 'respondingshoulders 35 onthe line contact member. The contact support 28 is shielded from theeects of arcing by a generally U-shaped ber insulating' piece 30.

Three movable contacts 36 are provided, each being rigidly attached tothe outer end of resilient contact arms 37 which vin turn are rigidlyattached Vto an insulating contact Vcross arm 38. The contactsupporting'arms V37 are preferably shielded by insulation 'strips V39asshown.

The insulating contact cross arm is supported for movement by -agenerally U-shaped contact operating member 40. The contact operatingmember V40 is provided with two aligned slots 41 adjacent the bightthereof, and the contact cross arm 38 extends through the yalignedslots1411and^isrigidly attached to the bight of the'contact operator 40by suitable means such as 4by rivets 42. It will be observed howeverlthat the contactcross arm 38 is supported on the operating member-40-at three points,=i.'e., against the bight portion of thecontactoperatorf40 andlagainst the Yedgesof the slots 41 formed VintheLside portions .of thecontact operator 40. This supportingarrangement not. only distributes the stress exertediqon the contactcross arm 38 by the lcontactoperator `40, but also `restrainS anytendency of lthe vcontact cross arm 38 toward warping or twisting. Thecontact operating `member v40 is supported inthe tophousing 'member1f0-,for rotation about a fixed pivot 43 and'is adapted to be.operatedbetween openfandclosed circuit positions ina manner and `bymeans'toibe described. The. `CirCuitfbrealter ofmyinventionalso-includeS-three loadfconriectins terminalseach,,comprising-a.leadterminal strap 44 which is generally L-shaped and hasits outer extremity bent downwardly to retain thereon a generallytubular wire clamping member 45 which may be of steel, and which carriesa-wire clamping screw 46. The load terminal strap 44 has its innerportion extending within each of the recesses 15, 16 and 17 of thevtophousing member 10 respectively and is anchored to the top housing memberby a clamping screw 47 extending through a slot 48 in the end wall ofthe top housing member 10 (see particularly FIGURES 8 and 10) and intothreaded engagement with the vertical portion of the load terminal strap44.` The extreme inner end 49 is return-bent, and has ixedly attachedthereto an elongated bimetallic strip 50. For the purpose of adjustingthe normal position of the bimetallic strip 50 with respect to thetinsulating housing member 10, I provide a Calibrating screw 51threadedly engaging the vertical portion of the terminal strap 44 andadapted to exert a pressure against the upper portion of the bimetallicstrip 50. For the purpose of preventing current ilow through theCalibrating screw 1, aninsulating member 5-2 is provided which isgenerally T-shaped and adapted vto extend through an opening 49 in thebight portion of the return-bent portion 49 of the terminal strap 44.-The lower end of the bimetallic strip 50 is connected by a exibleelectrical conductor 53 to the movable contact 36.' For the purpose ofprotecting the ilexible conductor 53 from the eifects of arcing, Iprovide an insulating sheath of woven glass fiber material 54.

The exible braid 53 is attached to the contact supporting arm 37directly behind the movable contact 36. It will be observed, especiallyby reference to FIGURE '1, compared to FIGURE 2, that the exible braidundergoes a severe sharp bending immediately adjacent the movablecontact 36. This bending is so sharp that, with ordinary methods ofattachment, breakage would occur in the ilexible conductor at this pointafter a number of operations of the breaker. Such breakage is preventedin the present design however by means of a supplementary supportingclip 55. The clip 55 includes a generally U-shaped portion, the outerends of the U being bent over the edges of the contact supporting arm37, and the intermediate portion of the U encircling the flexibleconnector immediately adjacent the point at which it is welded to themovable contact. The clip 55 further includes a return-bent portionextending from the bight of the U and adapted to engage the flexibleconnector and to prevent the connector from bending too sharply at thispoint of connection, (see particularly FIGURE l and FIGURE 3).

' The current path may now be traced through the circuit breaker in thefollowing sequence:

Current enters at the line contact Z5 and goes to the stationary contact29, to the movable contact 36, through the end portion of the contactsupporting arm 37 tofthe flexible conductor 53, to the bimetallic strip50, to the load terminal strap 44.

For the purpose of moving the contact operator 40 about its pivot 43 tomove the movable contacts between open and closed circuit positions, andto releasably retain such contacts in the closed circuit position, Iprovide a circuit breaker operating mechanism 56 shown in perspective inFIGURE 5 and shown in exploded relation in FIGURE 6.

The operating mechanism includes two opposed side frame members 57 and58, supported in spaced-apart relation by spacer pins 59 and 60. Thespacer pins 59 and 60 include shouldered portions for supporting andspacing apart of the side frame members and also integral extensions 61and 62 adapted to project through the side frame members and to extendoutwardly from the outer side of such frame members for a purpose to bedescribed.

A releasable carrier member 63 is supported for pivotal movement betweenthe side frames 57 and 58 on a carrier pivot pin 64. The carrier pivotpin 64 is also shouldered and aids in spacing the side frames 57 and 58.Upper and lower pairs of toggle flinks 65 and 66 respectively are alsoprovided. The upper pair of toggle links 65 extend-one on each side ofthe carrier 63 and are pivotally supported thereon at one end by a pivotpin 67. The lower pair of toggle links 66 are more widely spaced apartand are individually pivoted on the U-shaped contact operator 40 byshort pivot pins 68. The upper and lower pairs of toggle links 65 and 66have their mutually adjacent ends connected and supported by a toggleknee pin 69. The upper toggle links 65 are pivotally supported on acentral enlarged portion of the pivot pin 69, and the more widely spacedlower toggle links 66 are pivotally supported on reduced outer portionsof the pivot pin 69. The pivot pin 69 is terminated at the outer surfaceof the lower toggle links 66 and is headed over to retain the links 66thereon.

A pair of tension-type operating springs 70 are supported at one end ingrooves in a relatively stationary spring anchor pin 71 which extendsfrom side-to-side of the mechanism and has reduced end portions 72resting in notches 73 cut in the corners of a projecting portion of themanually `operating member 74. The lower ends of the operating springs70 are attached to the toggle knee pivot pin 69, on the portion of thepin between each of the adjacent ends of the upper and lower togglelinks. The manual operating member 74 is pivotally supported onknife-edge type pivots by means of notches 75 therein adapted to rest onoutwardly bent lug portions 76 integral with the side frame memberes 57and 58 respectively. The manual operating member 74 is provided with amanually engageable insulating handle portion 77 having a portionadapted to project through an aperture 78 in the top wall of the tophousing member 10 and having an arcuate enlarged portion within thecasing housing adapted to close the remaining portion of the aperture 78in all positions of the` handle. The insulating handle member 77 isadapted to be carried by the operating member 74 and to operate themember 74 by means of intertitting portions including shoulders 79 onthe insulating handle 77 and edge portions 80 of the operating member74. For the purpose of facilitating assembly of the operating mechanismand the insulating handle 77 into the top housing member 10 in a mannerto be described, a temporary holding clip 81 (see FIGURE 6) is provided,comprising a generally U-shaped length of resilient wire having portionsbent over so that its side portions are L-shaped, and hooked in underthe top bight portion of the handle member 74. The handle member 74 hasa portion of the bight thereof lanced out and offset from the generalplane thereof thereby providing an opening to receive the clip 81 andalso a support to prevent the clip 81 from falling within the operatingmember 74.

Assuming the carrier member 63 to be stationary in the position shown inFIGURES l and 2, the switching action of the operating mechanism may bedescribed as follows. In `FIGURE l the parts are shown with the movablecontact in the open circuit position and the toggle links `65 and 66 inthe collapsed condition. As the handle member 77 is moved forward torotate the operating member 74 in a clockwise direction, the upper endsof the operating springs 70, carried by the spring anchor pin 71 arecarried in a clock-wise direction until the line of action of thesprings 70l passes across the pivot pin `67 of the upper toggle links65. When this occurs, the springs 70 exert a force on the toggle kneepin 69 urging it to the right as viewed in FIGURES l and 2, toward atoggle straightened position. The parts then quickly move to theposition shown in FIGURE 2, with a snap action. In this position, theresilient contact arms 37 are sligfhtly deformed, exerting apredetermined contact pressure between the movable contact 36 and thestationary contact 29. Conversely, when the handle member 77 is moved tothe left as viewed in FIGURES l1 and 2, the upper ends of the operatingsprings 70 are carried in a counterclockwise direction and when the lineof action of the spring 70 passes across the pivot pin 67, the togglelinks move to a collapsed position with `a 7 snap action and the pantsreturn to the normall ott position shown in FIGURE 1. For the purpose ofrelasably restraining the carrier member 63 in the normal or latohedposition shown in FIGURES l and 2, I provide a retaining latch 83,pivoted between the side frame members 57 and 58 at 84, and having anaperture 8S adapted to receive a latching portion 86 of the carrier 63.

For permittingthe operation of the latch member 83 by any one of two ormore trip devices in a manner to be described, I provide an insulatingcommon-trip bar 87 which extends transversely across all three polecompartments 20, 21 and 2.2 of the bottom housing member 11. Thecommon-trip bar 87 is preferably formed of a highly arc resistant andheat resistant material so as to withstand the effects of arcing fromthe arc chambers and to shield the current responsive trip assembly (tobe described). Suitable materials for the trip bar 87 includeglass-bonded mica or Mycalex, polyester and epoxy molding compoundsreinforced by glass fiber, plastic resin bonded asbestos, and ceramicmaterials such as porcelain and bonded alumina. The common-trip bar 87is rigidly attached to the retaining latch 83 by suitable means such asby rivets 88, and has a central portion 89 provided `with a hole 90adapted to receive one end of a trip bar biasing spring 91, the otheryend of which is anchored on tlhe frame spacer pin 59. The action of thetrip bar biasing spring 91 is such as to constantly bias the common-tripbar and the latch member 83 in a clockwise direction into latchingengagement with the latch portion 86 of the releasable carrier 63.

. It will be observed that in the normal off and on conditions shown inFIGURES l and 2 respectively, the operating springs 70 are undertension, placing the upper toggle links 65 in compression and exerting aforce on the releasable carrier 63 through the pin 67, which tends tomove the releasable carrier `63 in a clockwise direction as viewed inFIGURES l and 2. Such movement of the carrier 63 is normally restrainedby the latching engagement of the projection 86 with the retaining latch83. p For` the purpose of providing both thermal and magnetic currentresponsive tripping action, I provide each pole of the circuit breakerwith a bimetallic strip 50 described above, adapted to carry currenttherethrough, and, in addition, a magnetic armature member 110. Thearmature 110, shown more clearly in `exploded view FIGURE i6 includes abifurcated main portion terminating in upper bearing surfaces 111 eachadapted to pivot in knife-edge fashion in molded bearings 112 (see FIG-URE 4) in the top housing member 10. The armature 110I is retained inmounted engagement in the V-shaped pivot bearings 112 by means of anarmature biasing spring 113, which has one end hooked into a lanced-outportion V114 of the load terminal strap 44, and has the other endconnected by an insulating link 115 to a projecting tongue 110 integralwith the lower portion of the armature 110. The magnetic armature 110 isfurther provided with an integral offset ag-shaped portion 116 havingits outermost portion bent downwardly so as to present an edge 117 whichis adapted to extend in front of the lower extremity of the bimetallicstrip 50. The armature biasing spring 113 biases the armature 110 in aclockwise direction and normally maintains the edge 117 against theforward surface of the bimetallic strip 50=.

A magnetic core member 118 is also provided, being attached to the lowerportion of the bimetallic strip 50 by suitable means such as by welding,and is generally U-shaped to present pole portions 118' at either sideof the bimetallic strip 50i.

The operation of the thermal and magnetic trip device is as follows.Assuming the breaker to be in the closed circuit condition of FIGURE 2,during a continued overload condition which is below a short circuitvalue, tlhe bimetallic member 50` is ,heated by the aotion of currentpassing Etherethrough, and deflects or warps in a way to causfefthe`lofwer end thereof to move Vto lthe Vright as viewed in FIGURES l and2. As the lower end of the 8 bimetallic strip 50 moves to the right, itengages .the `edge 11,17 of the armature 1:10 and carries the armature110 with it, until the toe portion of the armature ,extension l116engages the common-trip bar 87. Continued move,- ment of the bimetal 50and the armature 110 to the right moves the lower end of the trip bar 87to the right, rotating `the latchmember 83 in a `counercloclcwisedirection and withdrawing the retaining edge of the aperture from thelatch portion 86 of the carrier 63. Upon release of the latch portion86, the operating springs 70 move the carrier member 63' in a clockwisedirectian until the extension 119 on the carrier 63 strikes the spacerpin 60.

As this rotation of the carrier member 63 occurs, the pivot pin 67 ofthe upper toggle links is carried across the line of action of theoperating springs 70, thereby reversing the rotational bias of theoperating springs 70 on the upper toggle links, collapsing the togglelinks and moving the movable contacts to the open circuit position asshown in FIGURE 3. The movement of the movable contact operator andcontact arms toward the open circuit position is limited -by the contactoperator 40 striking the pivot pin 64 of the carrier member 63. Thistripping .action occurs regardless of whether the movable operatinghandle 77 is forcibly restrained in the on position such as by a-noperators hand. When the operating handle 77 is released, however, thehandle member 77 is automatically returned to a central position asindicated in FIGURE 3 by further action of the .operating spring 70.This handle-return action takes place because the lower ends of theoperating springs 70 have been moved to the left by the collapsingaction of the toggle links, and therefore the line of action of theoperating springs 70 now passes to the left hand side of the handlepivot point 75 as viewed. This return movement ofthe manual operatingmember 77 counterclockv wise as described, is limited by the engagementof .a resetting pin 120 carried by and extending from side-to.- side ofthe manual operating member 74, which pin engages a resetting camportion of the edge of releasable member 63. v

In order to reset the circuit breaker, (assuming that the bimetallicmember 50 has cooled suciently .to permit the latch biasing spring 91 toreturn the latch member 83 to proper position) the manually engageablehandle portion 77 is moved manually from the central position or tripposition of FIGURE 3 to the normal ott or resetting position ofFIGURE 1. During this movement, the resetting pin 120 rides along theresetting cam portion 121 of the carrier 63 and rotates the carrier 63counterclockwise about its pivot 64 until the latching projection 86once again enters the aperture 85 in the latch 83. At this point, thelatch biasing spring 91 returns the latch 83 to its extreme clockwiseposition, such clockwise movement being limited by the engagement of theportion of the latch 83 immediately below the aperture 85 with the edgeportion of the carrier member 63 immediately below the latchingprojection 86, assuring a xed, predetermined maximum` latch engagement.

Instantaneous or magnetic tripping action occurs when currents of ashort circuit magnitude pass through the circuit breaker and through thebimetallic strip 50. When this occurs, the magnetic eld associated withsuch current forms magnetic poles at 118 of the core member 118, therebycreating an attraction between the armature and the magnet 118. Sincethe bimetallic strip 50 is relatively stili compared to the resilienceofthe magnetic armature biasing spring 113, the armature 110 movestoward the bimetallic strip 50 and toward the magnet 118. When thisoccurs, the toe portion of the armature extension 116 engages the commontrip bar 87 and Vrotates the latch member 83 in counterclockwisedirection, causing tripping inthe same manner as described above.Resetting following such magnetic tripping is 9 accomplished in the samemanner as previously described in connection with thermal tripping.

As mentioned above, the exact calibration of the circuit breaker may bealtered by adjusting the Calibrating screw 51 which exerts a forcebetween the main portion of the terminal strip 44 and return-bentportion 49 which carries the bimetallic strip, either opening it outwider or allowing it to return to a more nearly closed position byreason of its resilience. This adjusts the angular position of thebimetallic strip 50 with respect to the remaining parts of the circuitbreaker and particularly with respect to the common trip bar 87.

In FIGURE 12 I have shown a modied form of common trip bar. In thismodification, the common trip bar 122 instead of being formed entirelyof insulating material, is formed of a metallic material such forinstance as aluminum, which is coated with a suitable coating 122 ofinsulating material comprising an epoxy resin plastic.

In order to support the operating mechanism of my improved circuitbreaker in such a manner as to protect it from the effects of arcinterruption in the closelyadjacent arc interrupting chamber, I havedevised an arrangement and supporting means whereby the completelyassembled mechanism is inserted and supported in the upper half of theinsulating housing, that is, in housing member 10, and I have likewisedevised means whereby the trip devices for each of the three poles ofthe circuit breaker is also supported in the upper half of theinsulating casing, that is in housing member 10, and particularly issupported in such housing member with respect to the operating mechanismand its associated latch and trip bar. Accordingly the operatingmechanism is provided with relatively short projections 61 and 62described above extending outwardly from the outer surfaces of the sideframe portions 57 and 58. In addition, the central chamber 16 of theupper housing member is provided with two pairs of recesses or slots 123and 124 `adapted to receive the projections 61 and 62, respectively. Theslots 123 and 124 are also provided with in intermediate portion whichis slightly constricted so as to alord a defeatable resistance to theentry of the projections. In addition, each of the side frame members 57and 58 is provided with integral vertically deformable portions 125 fora purpose to be described.

The distance between the side frames 57 and 58 is preferably made lessthan the corresponding distance between the barriers 23` and 2.4 of thelower housing member 11, so that in the two pole form the width of thecircuit breaker may be reduced to effectively twothirds that of thethree pole form without interfering with the mounting and support of theoperating mechanism thus permitting the same mechanism to be used forboth the two and three pole forms. For the purpose of supporting themechanism in the upper housing member 10 and in the downwardly openingyslots 123` and 124, as well as for the purpose of further isolating theoperating mechanism from the arcing products produced in the lowerchambers, I provide `arc extinguishing chamber covers 126. Each of theare .extinguishing chamber covers 126 is supported on ledges 127 in eachof the recesses 20, 21 and 22, and has a slot cut therein to permit theentry of the contact operating arms `37 in the outer pole chambers 20and 22, the arc extinguishing covers 126 serve primarily to isolate theeffects of arcing in each of the associated chambers. In the centralchamber 21, the arc extinguishing cover 126 performs this same functionand in addition provides a supporting base which is adapted to engagethe deformable portions 125 of the side frame members 5-'7 and 58 and tothereby hold the operating mechanism in its proper location in the upperhousing member 10.

The two deformable portions 125 are initially formed so as to extendbelow their nally assembled position,

so that as the housing members are placed together and suiicient forceis exerted, the portions 125 are deformed slightly, thereby providing aresilient retaining `force to retain the mechanism in position. l

The assembly of the complete three pole circuit breaker thereforepreferably follows the following sequence. First the operating mechanismis assembled between the side'frames 57' and 58 with the movable contactarms and movable contacts, and also with the flexible conductors 53 andeach of the bimetallic strips 50 and load terminal straps 44 andconnectors 45 attached thereto. The handle member 77 is inserted inplace on the manual operating member 74 being resiliently retainedthereon by the retaining clip 81. The top housing member 10 may then beinverted and the assembled mechanism inserted therein so that theprojections 61 and 62 rest in the entrance portion of the slots 123` and17A. Additional manual pressure upon the side frames 57 and 58 causesthe projections 61 and 62 to snap into their nal location in the extremeportion of the slots 123 and 124. This subassembly may therefore beconveniently handled before the addition of the lower housing member 11without the mechanism falling out. The trip devices including thebimetallic strips and load terminal straps are then inserted intocorresponding recesses in the top housing member 10, the load terminalstrap mounting screw 47 being already inserted in its threaded holetherein, such assembly being permitted by the entrance slot 48. The loadterminal s-trap mounting screw 48 is then tightened mounting the loadterminal member and bimetal in xed position in the upper housing member.Following this,

-the armature members are assembled by hooking the extension portions116- around the extreme end of the bimetallic strips 50 and placing thebearing edges 111 in the corresponding molded bearings 112 in thecasing, and by hooking the armature biasing spring in position betweenthe terminal strap and the armature.y It will be observed .that thearmature biasing spring 113` serves not only to bias the armature member11() into mounted condition in its inverted V-shaped bearings in theupper housing member, but also to bias it clockwise so that the edge 117is normally maintained in proper engagement with the surface of thebimetallic strip 50. Following assembly of the parts in the upperhousing member 10, the arc extinguishing assemblies comprising thesupport member 30, the arc plates 31, and the line contact member 25carrying the stationary contact 29 are assembled as one unit into thecorresponding recesses in the lower housing member 11. The arcextinguishing cover members 126 are then placed over the areextinguishing assemblies. The circuit breaker is then ready for thefinal assembly operation and is in the condition shown in FIGURE 9'. Thetop and bottom housing members are then brought -together and suflicientforce exerted to deform the deformable portions of the side frames 57and 58 `and rivets 12 are passed through the aligned holes 14 in the topand bottom housing members and spun over to retain the part-s together.I-t will be observed that following such nal assembly, the clampingmember 45 encircling the load terminal strap 44 and the tubular clampingmember 45 are supported by an insulating piece which in turn issupported by projecting bosses 128 projecting from extensions of theside wall portions and of the barrier portions 23, 24 of the bottomhousing member 11. In the form shown in FIGURE 8, the strap 44 and themember 45 are supported directly bfy the bosses 128 and the piece 130 isomitted.

The completed circuit breaker is adapted to be held in mounted conditionby suitable retaining means (not shown) adapted to engage projectingledges 129 below the load terminal members 45. The design of the ledgemembers 129 and the bosses 128 is such as to remove the necessity forAundercutting in the molding of the bottom housing member 11. Accordinglythe design is such that no part of the lower housing member Il.

2 l 11 projects ldirectly above the ledge 4surface 12.9, the b osses 128,being offset to one side of such vertical location. It will ybeobserved that the design of the housing is such that top and bottommating housing members and 11 are provided each including threeregistering longitudinal recesses 15, 16, 17 and 20, Z1, 22 separated byregistering barriers 18, V19` and 23, 24, and that these recesses eachof which ser-v es as a separate pole chamber, are crossed by atransverse passageway, the transverse passageway .being offsetlongitudinally and located at opposite ends of the circuit breakerproper. In this manner maximum isolation and maximum compactness isachieved.

The tapering construction of the slots 123 and 124 provides for easyandrapid insertion of the assembled mechanism in place in the topVhousing member 10 and also provides accurate nal'positioning. By meansof the assembly shown the operating mechanism including its supportingframe members is mounted in the insulating casing without beingpositively fastened thereto. This construction s aves a considerableamount of time and expense in assembly `of the circuit breaker. Inaddition, it provides a safer construction than those utilizing screwsgoing through the housing which need to be insulated from outside thehousing.

The manual operating member 74 is generally U-shaped and the sidesthereof oxtend alongside of the mounting side frames S7 and 58 of theoperating mechanism. Space or clearance must therefore be providedbetween the inner walls of the mounting chamber 16 and the sides -of theframe members 57 and 58 to allow free movement of the manual operatingmember 74. This spacing is also provided by the extended projections 61and 62.

It will be observed that, although the operating mechanism, the tripdevices and the arc extinguishing chamers are all contained in a verysmall volume of space, the critical parts of the operating mechanism andtrip devices such as the operating springs and the bimetallic strips,yare well protected from the effects of the `nearby arcing by theplacement and configuration of other parts.

e The `common trip bar 87, for instance, is preferably made inthe formof a relatively wide, thin, at member so that it is adapted to act as ashield interposed between the entrance portions 33 of the `arcextinguishing chambers and each trip device including bimetallic strips50 and magnetic core 118.

The contact cross-arm 38 and the contact arms 37 are likewise relativelywide, thin, and at, yand act as shielding `means to assist in shieldingthe mechanism from the effects of arc interruption, It will be observedfor instance that the central contact arm is always between thearcextinguishing chamber and the operating springs 70. The design of thecircuit breaker housing and especially thelower housing member 1 1 issuch as to provide substantially no venting from the arc extinguishingchamber outside of the casing. This total enclosure affords maximumsafety to surrounding apparatus while much ofthe hot air and gasesgenerated by arc interruption are forced out of the entrance 33 againstthe iiexible conductor 53 and toward the trip device, serious damage isprevented to these parts. Damage to the flexible conductor 53 isprevented although it is directly in the stream of `arc extinguishinggases by reason of the fiexible woven glass sheath 54. It has been foundthat although the temperature of theflame and gases is suiiicient tomelt such glass and produce a sizable vhole in such a sheath, that eventhereafter the affect of such flame and gases on t-he conductor 53 isnot `further destructive. This is assumed to be because the melted glasscoats the individual strands of the flexible conductor affording itprotection.

In 'FIGURE l3 el have shownmy invention asembodiedgin a two-,polecircuit breaker. The construction of this form is substantial-lyidentical to that of FIGURE 12 1 excepting that the casing includes onlytwo pole chambers, and the contact cross-arm 37 and the common trip bar87 are shortened accordingly. i

While I have shown only two embodiments of my `invention, it willbereadily appreciated that many modifiI cations thereof may easily bemade, and -I Aintend therefore, by the appended claims, to cover allsuch modifications as fall within the true spirit and scope ofmy'invention.

What I claim as new and desire to secure by lLetters Patent of theUnited States is:

l. An electric circuit breaker comprising a generally rectangularinsulating casing having an apertured `top wall, a bottom wall, frontand rear walls and opposed side walls, a stationary contact supported ina cornerV of said casing adjacent said front and bottom walls,`a movablecontact arm pivotally ksupported on a iixed pivotal axis said fixedpivotal axis being closer to said top wall than to said bottom wall,said contact arm extending generally downwardly from said pivotalsupport toward said bottom wall and moving about said support along anarcuate path toward and away from said frontwall, a movable contactcarried by said contact armand movable thereby into and out ofengagement with said stationary contact, operating mechanism comprisinga manually operable handle member pivotally supported Von a iixedpivotal axis and including an insulating handle portion projectingthrough said aperture in said top wall, a releasable trip memberpivotally supported' ,on a fixed pivotal axis, a toggle linkageconnected at one end to said releasable trip member and at the other endto said movable switch arm, spring means interconnecting said manuallyoperable handle member and the knee ,of said toggle linkage, latch meansnormally restraining said rcleasable trip member from movement in apredetermined direction, and current responsive means including ap0rtion adapted to engage said latch means to cause movement thereof torelease said releasable means upon the occurence of predeterminedelectrical conditions.

2. An electric circuit breaker as set forth in -claim l wherein thepivotal axis of said movable switch arm lis also closer to said frontwall than to said rear wall of said casing.

3. In a multipole electric circuit breaker comprising a generallyrectangular insulating housing comprising a top wall having ahandle-receiving aperture therein anda bottom wall opposite said topwall, a plurality of' sideby-side pole chambers in said housing, an arcextinguishing chamber in the portion of each of said pole chambersadjacent said bottom Wall, a pair of relatively movable contacts in eachsaid arc chamber, operating meehanism for said relatively movablecontacts comprising a manually operable handle supported on a fixedpivotal axis in said housing, a movable trip member supported on a fixedpivotal axis in said housing and movable to cause automatic opening ofsaid contacts, a contact operating member supported on a fixed pivotalaxis in said housing between said arc extinguishing chambers and saidtop wall, a pair of interconnected toggle links connected at one end tosaid contact operating member and at the other end to said movable tripmember, and overc'enter spring means interconnecting said handle memberand said togglev links.

4. The invention as set forth in claim 3 wherein the operating mechanismis contained in one of said pole chambers, and the contact operatingmember includes a portion extending across all of 4said pole chambers.

5. An electric circuit breaker comprising a switch member pivotallysupported on a fixed pivotal axis-at one end and carrying a relativelymovable contact at the other end, a stationary contact adapted Ato becontacted by said movable contact, means for operating said movableswitch member 'between open and'closed circuit positions including a4toggle linkage operatively connectedtosaid movable switch larm at oneend, [a releasable trip member pivotally supported on afixed pivotalaxis and having a latch projection, latch means for releasablyrestraining said latch projection in latched position, means supportingthe other end of said toggle linkage on said releasable trip member, thepivot point of said releasable trip means and the pivot axis of saidmovable switch member lying on the opposite side of the line joining theends of said toggle linkage from said latch projection when said togglelinkage is in said straightened condition.

6. An electric circuit breaker comprising a relatively stationarycontact, a movable switch member pivotally supported on a stationarypivotal axis, a movable contact carried by said movable switch memberand adapted to be moved thereby into and out of engagement with saidstationary contact, manually operable handle means supported on arelatively stationary pivotal axis, and movable between on and offcircuit positions, a releasable trip member pivotally supported on arelatively stationary pivotal axis at one end and having a latchprojection, latch means normally engaging said latch projection andrestraining said releasable trip member from movement in a predetermineddirection, current responsive means for causing releasing movement ofsaid latch member to cause release of said releasable member, a togglelinkage operatively connected to said movable switch arm and operablebetween collapsed and straightened conditions to operate said movableswitch arm between open and closed circuit conditions respectively,means operatively connecting said manually operable handle means andsaid toggle linkage to permit operation of said toggle linkage betweensaid collapsed and straightened conditions by said manually operablehandle member, the pivotal axis of said releasable trip means and ofsaid movable switch member both lying on the side of said toggle linkageopposite from said latch projection when said linkage is in saidstraightened condition.

7. An electric circuit breaker comprising an insulating housing, atleast one pair of relatively movable contacts in said housing, operatingmeans in said housing for operating said contacts comprising a manuallyoperable handle member pivotally supported for movement about a fixedpivotal axis, a contact operating member pivotally supported formovement about a fixed pivotal axis, a releasable member supported formovement about a fixed pivotal axis and having a latch projection, apair olf toggle links interconnecting said contact operating member andsaid releasable member, overcenter spring means interconnecting saidmanually operable member and the knee of said toggle, the pivot point ofsaid contact operating member and the pivot point of said releasablemember being on the side of the line generally defined by '14 saidtoggle links opposite from said latch projection in their straightenedcondition.

8. An electric circuit breaker comprising an insulating housing, amanually operable handle member pivotally supported on a fixed pivotalaxis in said housing, a releasable -trip member pivotally supported insaid housing on a yfixed pivotal axis at one point and releasablylatched against movement relative to said housing at another point, amovable switch member pivotally supported on a fixed pivotal axis insaid housing, an operating linkage including a pair of interconnectedtoggle links connected at one end to said movable switch member and atthe other end to said releasable member, resilient spring meansconnected between the knee of said toggle links and said manuallyoperable member, the fixed pivotal axis of the movable switch memberbeing immediately adjacent the iixed pivotal axis of said releasablemember, said switch member axis and said releasable member axis being onthe side of the line generally defined by said toggle links in theirstraightened condition opposite from said latched point of saidreleasable member.

9. An electric circuit breaker comprising an insulating housing, amanually operable handle member supported in said housing on a fixedpivotal axis, a movable switch member supported in said housing on afixed pivotal axis, a releasable trip member supported on a fixedpivotal axis in said housing at one point and releasably latched againstmovement with respect to said housing at another point, an operativeconnection between said manually operable handle member and said movableswitch member including a pair of toggle links and resilient springmeans, said toggle links being movable between straightened andcollapsed positions to move said movable switch member between closedand open positions, the fixed pivotal axes of said movable switch memberand said releasable member being on the opposite side of the linedefined by said toggle links when in their straightened condition, saidlatched point of said releasable trip member.

References Cited in the file of this patent UNITED STATES PATENTS2,013,827 Jennings Sept. l0, 1935 2,050,285 Dorfman A-ug. l1, 19362,059,985 Frank et al Nov. 3, 1936 2,329,053 Jennings Sept. 7, 19432,624,816 Gingenheimer t Jan. 6, 1953 2,669,627 Gelzheiser Feb. 16, 19542,695,345 Scott Nov. 23, 1954 2,783,330 Casey Feb. 26, 1957 2,811,607Dorfman Oct. 29, 1957

